Network Working Group L. McIntyre
Request for Comments: 3250 Xerox Corporation
Category: Standards Track G. Parsons
Nortel Networks
J. Rafferty
Brooktrout Technology
September 2002
Tag Image File Format Fax eXtended (TIFF-FX) - image/tiff-fxMIME Sub-type Registration
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2002). All Rights Reserved.
Abstract
This document describes the registration of the MIME sub-type
image/tiff-fx. The encodings are defined by File Format for Internet
Fax and its extensions.
1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [REQ].
2. Overview
This document describes the registration of the MIME sub-type
image/tiff-fx. The encodings are defined by File Format for Internet
Fax [TIFF-FX] and its extensions.
3. Internet Fax Working Group
This document is a product of the IETF Internet Fax Working Group.
All comments on this document should be forwarded to the email
distribution list at <ietf-fax@imc.org>.
McIntyre, et. al. Standards Track [Page 1]

RFC 3250 image/tiff-fx September 20023. TIFF-FX Definition
TIFF-FX (Tag Image File Format Fax eXtended), is defined in detail by
RFC 2301 "File Format for Internet Fax" [TIFF-FX].
While a brief scope and feature description is provided in this
section as background information, the reader is directed to the
original TIFF-FX specification (File Format for Internet Fax) to
obtain complete feature and technical details.
3.1 TIFF-FX Scope
This document defines a TIFF-based file format specification for
enabling standardized messaging-based fax over the Internet. It
specifies the TIFF fields and field values required for compatibility
with the existing ITU-T Recommendations for Group 3 black-and-white,
grayscale and color facsimile. TIFF has historically been used for
handling fax image files in applications such as store-and-forward
messaging. Implementations that support this file format
specification for import/export may elect to support it as a native
format. This document recommends a TIFF file structure that is
compatible with low-memory and page-level streaming implementations.
Unless otherwise noted, the current TIFF specification [TIFF] and
selected TIFF Technical Notes [TTN1, TTN2] are the primary references
for describing TIFF and defining TIFF fields. This document is the
primary reference for defining TIFF field values for fax
applications.
3.2 TIFF-FX Features
Some of the features of TIFF-FX are:
- TIFF-FX is capable of describing bilevel, grayscale, palette-
color, full-color and mixed content image data.
- TIFF-FX includes a number of compression schemes that allow
developers to choose the best space or time tradeoff for their
applications.
- TIFF-FX is designed to be extensible and to evolve gracefully
as new needs arise.
McIntyre, et. al. Standards Track [Page 2]

RFC 3250 image/tiff-fx September 20024. MIME Definition
This document defines the image/tiff-fx MIME sub-type to refer to
TIFF-FX Profiles J, C, L and M encoded image data and any future
TIFF-FX extensions, or a subset. The image/tiff-fx content type may
be used when black-and-white image data is encoded using TIFF-FX
Profiles S or F, or a subset.
5. IANA Registration
To: ietf-types@iana.org
Subject: Registration of Standard MIME media type image/tiff-fx
MIME media type name: image
MIME subtype name: tiff-fx
Required parameters: none
Optional parameters: none
Encoding Considerations: This media type consists of binary
data. The base64 encoding should be used on transports that
cannot accommodate binary data directly.
Security considerations:
TIFF-FX utilizes a structure which can store image data and
attributes of this image data. The fields defined in the
TIFF-FX specification are of a descriptive nature and provide
information that is useful to facilitate viewing and
rendering of images by a recipient. As such, the fields
currently defined in the TIFF-FX specification do not in
themselves create additional security risks, since the
fields are not used to induce any particular behavior by the
recipient application.
TIFF-FX has an extensible structure, so that it is
theoretically possible that fields could be defined in the
future which could be used to induce particular actions on
the part of the recipient, thus presenting additional
security risks, but this type of capability is not supported
in the referenced TIFF-FX specification. Indeed, the
definition of fields which would include such processing
instructions is inconsistent with the goals and spirit of the
TIFF-FX specification.
McIntyre, et. al. Standards Track [Page 3]

RFC 3250 image/tiff-fx September 2002
Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
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Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
McIntyre, et. al. Standards Track [Page 7]